Arc welding cable

ABSTRACT

An arc welding cable that is resistant to bending and twisting and can give a long life is provided. For this purpose, an arc welding cable ( 65 ) for supplying a welding current, a welding wire and a sealed gas from a wire feeding device ( 61 ) to a welding torch ( 64 ), has a passage ( 4 ) for the welding wire ( 2 ) and sealed gas is located at a center of the arc welding cable and a plurality of conductors ( 5 ) are arranged apart from one another on a circumference around the passage ( 4 ). The space between the plurality of conductor ( 5 ) may be filled with a cushion material such as cotton or elastic synthetic resin.

TECHNICAL FIELD

This invention relates to an arc welding cable for supplying a weldingcurrent, a welding wire and a sealed gas from a wiring feeding device toa welding torch.

BACKGROUND ART

A welding robot is now being widely used for performing arc welding witha welding torch for arc welding that is attached to the tip of avertical articulated robot.

FIG. 5 shows the outward appearance of this welding robot. In FIG. 5,reference numeral 51 denotes a vertical articulated robot; and referencenumeral 52 denotes its upper arm. a wrist 53 which can perform theoperation with three degrees of freedom (slewing, swing and rotation) isattached to the tip of the upper arm 52. Reference numeral 61 denotes awire feeding device. The wire feeding device 61 is fixed to the upperarm 52 to extract a welding wire 63 from a wire reel 62 and extrude thewelding wire 63 to a welding torch 64 attached to the wrist 53.Reference numeral 65 denotes a welding cable. The welding cable 65connects the wire feeding device 61 and the welding torch 64. Thewelding cable 65 is provided with a tubular passage at the centerthrough which a welding wire is passed. The welding cable 65 binds ahose for supplying a sealed gas, an electric wire for supplying awelding current and various kinds of signal lines, which are arrangedaround the tubular passage.

Meanwhile, in such a conventional welding robot, the wire feeding device61 is fixed to the upper arm 52. The welding torch 64 attached to thewrist 53, which performs the operation with three degrees of freedom,moves freely. The welding cable 65, therefore, repeats bending ortwisting. This presented a problem that the welding cable 65 might bebroken owing to stress.

Particularly, if the welding cable 65 is located near the upper arm 52and wrist 53 (as shown by dotted line in FIG. 5) in order that it doesnot interferes with objects in the vicinity of the robot 51 (e.g. awelding workpiece or jig), the bending radius is small and the length isalso short. The bending stress and twisting stress, correspondingly,become large. This presented a problem of further shortening the life ofthe welding cable 65.

DISCLOSURE OF THE INVENTION

This invention intends to provide an arc welding cable that is resistantto bending and twisting and can give a long life.

In order to solve the above problem, according to the present inventionof claim 1, there is provides an arc welding cable for supplying awelding current, a welding wire and a sealed gas from a wire feedingdevice to a welding torch, having a passage for the welding wire and thesealed gas is located at a center of the arc welding cable, wherein aplurality of conductors are provided so as to be apart from one anotheron a circumference around the passage.

Further, according to the present invention of claim 2, spaces definedamong the plurality of conductors are filled with a cushion material.

Further more, according to the present invention of claim 3, the cushionmaterial is cotton.

Further more, according to the present invention of claim 4, the cushionmaterial is an elastic synthetic resin.

Further more, according to the present invention of claim 5, theconductors are covered wires that are covered with an insulator.

Further more, according to the present invention of claim 6, a code madeof a fiber with a high tensile strength is located at a center of theconductor.

Further more, according to the present invention of claim 7, the arcwelding cable further has a shaft that is provided on an end portionthereof and engages with a socket of the wire feeding device or thewelding torch so as to pass the welding current and sealed gas, a firstcaulking portion that caulks with the conductors to electrically connectthe shaft with the arc welding cable and a second caulking portion whichcollectively caulks a hose for the sealed gas, the conductors and asheath of an outer layer of the arc welding cable onto the shaft tomechanically connect the shaft with the arc welding cable.

Further more, according to the present invention of claim 8, the eachconductor is a twisted pair wire having of a pair of a right-twistedstrand of wires twisted clockwise and a left-twisted strand of wirestwisted counterclockwise.

Further more, according to the present invention of claim 9, a part ofthe conductors is a signal line.

Further more, according to the present invention of claim 10, the arcwelding cables further has a cooling water hose, wherein a part of theconductors is replaced with the cooling water hose.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of an arc welding cable showing a firstembodiment of this invention;

FIG. 2 is a detailed cross sectional view of a conductor showing thefirst embodiment of this invention;

FIG. 3 is a longitudinal sectional view of the end of an arc weldingcable showing the first embodiment of this invention;

FIG. 4 is a cross sectional view of an arc welding cable showing asecond embodiment of this invention;

FIG. 5 is a view for explaining the configuration of a welding robot.

BEST MODE FOR CARRYING OUT THE INVENTION

Now referring to the drawings, an explanation will be given ofembodiments of this invention.

FIG. 1 is a cross sectional view of an arc welding cable showing a firstembodiment of this invention. In FIG. 1, reference numeral 1 denotes anarc welding cable; and reference 2 denotes a welding wire. The weldingwire 2 is fed from a wire feeding device (not shown) toward a weldingtorch through a conduit liner 3 located at the center of the arc weldingcable 1. Namely, the interior space of the conduit liner 3 constitutes awelding wire passage. Reference numeral 4 denotes a gas hose forsupplying a sealed gas to the welding torch not shown. Reference numeral5 denotes one of conductors arranged on the outer periphery of the gashose 4. In this figure, six conductors are arranged. The conductor 5 isa wire for passing a welding current. Reference numeral 6 denotes aholding tape wound around the outer periphery of the conductors 5.Reference numeral 7 denotes a sheath located at the outermost side ofthe arc welding cable 1 for sheathing the conductors 5. The sheath 7 ismade of PVC (polyvinyl chloride) with high heat-resistance, insulatingproperty and elasticity.

FIG. 2 is a detailed cross sectional view of the conductor 5. Theconductor 5 includes a code 8 of a fiber with a high tensile strength(e.g. Kevlar of DuPont™) arranged at the center, 6 (six) sets of strands9 arranged around the code 8 and 12 (twelve) sets of the same strands 9arranged further around them. The strand 9 consists of 7 (seven) sets oftwists each having 13 (thirteenth) tied soft iron wires each 0.8 mm indiameter. The conductor 5 has both softness and strength since thetensile strength is shared by the code 8.

FIG. 3 is a longitudinal sectional view of the end of an arc weldingcable showing the first embodiment of this invention. In FIG. 3,reference numeral 21 denotes a shaft that is a hollow cylinder ofbronze. The shaft 21 is fit in a socket of a welding torch not shown sothat a welding current is passed through the welding torch. The shaft isconnected to a gas hose 4 of the arc welding cable 1 through a cap 22 sothat a sealed gas flows through the cylinder portion.

Reference numeral 23 denotes a caulking pipe that is formed of a coppercylinder. In FIG. 3, at a portion A, the conductors 5 are locatedoutside the shaft 4, and a caulking pipe 23 is located outside theconductors 5. The conductors 5 are firmly crimped on the shaft 21through “caulking” by the caulking pipe 23. In this way, at the portionA, an electric connection is made between the conductors 5 and the shaft21. Incidentally, it is needless to say that at the portion A, the code8 (not shown in FIG. 3) at the center of the conductor 5 is alsosimultaneously crimped.

At portion B in FIG. 3, the gas hose 4 is located outside the cap 22;the conductors 5 are located outside the gas hose 4; and a sheath 7 islocated outside the conductors 5. The sheath 7, conductors 5 and gashole 4 are fixed to the cap 22 through “caulking” by the caulking pipe23. In this way, at the portion B, a mechanical connection is madebetween the arch welding cable 1 and the shaft 21. Namely, the force ofbending or twisting applied by the arc welding cable 1 is shared byportion B so that it is transmitted to the shaft 21. In the portion onthe right side of portion B, the conductors 5 are free from the gas hose4 and sheath 7 so that they are freely movable in the gap between thegas hose 4 and the sheath 7.

Reference numeral 24 denotes an insulating cover. The insulating cover24 is formed of a rubber cylinder, The insulating cover 24 covers theconnecting portion between the arc welding cable 1 and the shaft 21 sothat they are electrically insulated. Incidentally, the welding wire 2,conduit liner 3 and holding tape 6 are not shown in FIG. 3 in order toavoid complication.

As shown in FIG. 1, the conductors 5 are arranged in an annular space 10between the gas hose 4 and the holding tape 6. The space 10 between thesix conductors 5 is not filled with any material. The conductors 5,therefore, can be moved or deformed in the space 10. Thus, when thedeformation of bending or twisting is occurred on the arc welding cable1, the conductors 5 move in a direction of alleviating the bending ortwisting within the space 10. Accordingly, even when a large bending ortwisting is occurred on the arc welding cable 1, the conductors 5 sufferfrom only small stress.

FIG. 4 is a cross sectional view of an arc welding cable showing asecond embodiment of this invention. In FIG. 4, like reference numeralsrefer to like elements in the first embodiment. In FIG. 4, referencenumeral 11 denotes cotton filling the space between the sixth conductors5. The cotton 11 serves as a cushion material between the conductors 5.Namely, when the arc welding cable 1 suffers from bending or twisting,the cotton slowly deforms the conductors 5 and disperses the deformationof the conductors 5 so that it is not concentrated to a specific spot.When the bending or twisting has come loose, the deformation of theconductors slowly returns to the initial state by the action of thecotton 11.

The cotton 11 may be replaced by other material or substance as long ascushion that serves as a buffer. For example, various kinds of elasticsynthetic resins may fill the space between the conductors 5.

In the embodiments described above, the conductor 5 does not have acover, but it may be a covered wire. Further, the conductor 5 may be atwisted pair wire that is a set of two strands twisted in differentdirections (one twisted clockwise and the other twistedcounterclockwise). In the case of the twisted pair wire, when theconductor 5 suffers from twisting, the one strand is tightened whereasthe other strand is loosened. This increases the strength of theconductor against the twisting.

Further, a part of the six conductors 5 may be replaced by a signalwire, e.g. a signal wire for a shock sensor for detecting that thewelding torch 64 has collided with a workpiece. In this way, since thesignal wire that has been wired separately from the arc welding cable 1is integrated to the arc welding cable 1, possibility of breaking thesignal wire due to its snagging on the workpiece is reduced, and theappearance of the arc welding cable 1 is made neat.

Further, a part of the conductor 5 may be replaced by a hose for coolingwater for cooling the welding torch 64. Integration of the cooling waterhose to the arc welding cable 1 reduces the possibility of breaking thecooling water hose.

As understood from the description hitherto made, in the inventiondescribed in claim 1, a plurality of conductors are arranged apart fromone another on a circumference around the sealed gas passage. For thisreason, when the arc welding cable suffers from bending or twisting, theconductors move in a direction of escaping from the deformation due tothe bending or twisting, thereby reducing the stress due to the bendingor twisting. This presents an effect of increasing the life of thewelding cable.

In the inventions described in claims 2 to 4, the space between therespective conductors is filled with cotton or resin serving as acushion material. This alleviates concentration of the deformation ofthe conductors to a specific point, thereby presenting an effect offurther increasing the life of the welding cable.

In the invention described in claim 5, the conductors are defined ascovered wires. This presents an effect of preventing a danger ofelectrical leak even when the sheath is broken.

In the invention described in claim 6, a code made of a fiber with ahigh tensile strength is located at the center of the conductor. Thispresents an effect of providing the arc welding cable having bothmechanical strength and flexibility.

In the invention described in claim 7 includes a first caulking portionwhich electrically connects the shaft to the arc welding cable and asecond caulking portion which mechanically couples them so that externalforce is applied to the first caulking portion. This presents an effectof increasing the reliability of the electrical coupling portion.

In the invention described in claim 8, the conductor is defined as atwisted pair wire. This presents an effect of making the conductor moreresistant to twisting, thereby lengthening the life of the weldingcable.

In the inventions described in claims 9 and 10, the signal wire orcooling water hose is integrated to the welding cable. This presents aneffect of reducing danger of breaking the signal wire or cooling waterhose.

[Industrial Applicability]

This invention is useful as an arc welding cable for supplying a weldingcurrent, a welding wire and a sealed gas from a wire feeding device to awelding torch.

1. An arc welding cable for supplying a welding current, a welding wireand a sealed gas from a wire feeding device to a welding torch,comprising: a passage for the welding wire and the sealed gas, thepassage being located at a center of the arc welding cable, wherein aplurality of conductor is provided so as to be apart from one another ona circumference around the passage.
 2. The arc welding cable as setforth in claim 1, wherein spaces defined among the plurality ofconductors are filled with a cushion material.
 3. The arc welding cableas set forth in claim 2, wherein the cushion material is cotton.
 4. Thearc welding cable as set forth in claim 2, wherein the cushion materialis an elastic synthetic resin.
 5. The arc welding cable as set forth inclaim 1, wherein the conductors are covered wires that are covered withan insulator.
 6. The arc welding cable as set forth in claim 1, whereina code made of a fiber with a high tensile strength is located at acenter of the conductor.
 7. The arc welding cable as set forth in claim1, further comprising: a shaft that is provided on an end portion of thearc welding cable and engages with a socket of the wire feeding deviceor the welding torch so as to pass the welding current and sealed gas; afirst caulking portion that caulks with the conductors to electricallyconnect the shaft with the arc welding cable; and a second caulkingportion which collectively caulks a hose for the sealed gas, theconductors and a sheath of an outer layer of the arc welding cable ontothe shaft to mechanically connect the shaft with the arc welding cable.8. The arc welding cable as set forth in claim 1, wherein the eachconductors is a twisted pair wire comprising of a pair of aright-twisted strand of wires twisted clockwise and a left-twistedstrand of wires twisted counterclockwise.
 9. The arc welding cables asset forth in claim 1, wherein a part of the conductors is a signal line.10. The arc welding cables as set forth in claim 1, further comprising acooling water hose, wherein a part of the conductors is replaced withthe cooling water hose.